Typhoon Yancy (T9313), which was in the early gradual developing stage and moved westward over the northwestern Pacific near (19N, 129E), was observed by the Japan Meteorological Agency research vessel Keifu Maru, during 30 August to 1 September 1993. During that period, the circulation center of Yancy approached as close as 80 km to the north of the Keifu Maru. Convection in the major part of Yancy was analyzed using the radar, maritime weather and upper air observation data obtained on the ship and recently available satellite data. Cell echo tracking winds (CETwinds) were estimated and utilized to supplement low level wind data around Yancy.During the early developing stage, an in-concentric structure of Yancy in which a cloud system existed in a southwest quadrant of a lower-level cyclonic circulation (LLCC) of 1500 km scale was transformed to a concentric one through a formation of a central dense overcast ('CDO') in the cloud system. After the establishment of the concentric structure, Yancy began rapid development.Various mesoscale (100-500 km) precipitation features (MPFs) were organized and evolved successively within Yancy. The configurations of the MPFs were changed as the early developing process progressed through four sub-stages. In the initial sub-stage, a large (400 km) echo system (LES) was organized in the southwest quadrant of the LLCC, over which a round cloud system appeared. In the second sub-stage, a long lasting mesoscale intense convective area (MICA) was formed around the northwestern edge of the LES, which was a mesoscale precipitation entity of the 'CDO' in the round cloud system. LLCC appeared to be intensified on a 500 km scale after the formation of MICA. In the third sub-stage, LES and the cloud system evolved into a comma-shaped spiral band with length over 500 km in the intense cyclonic circulation. In the final sub-stage, curvature of the spiral band was increased and an inner near-circular spiral band emerged in the further intensified LLCC. The northern head of the comma-shaped cloud system was encircling the LLCC center. Line systems transversal and longitudinal to lower-level circulation were formed around MICA in the first sub-stage, and in the second sub-stage, respectively.